1. Field of the Invention
The present invention relates to a digital data recording apparatus, a digital data recording method, and a computer-readable recording medium for protecting copyrights of digital data.
2. Description of the Related Art
Thanks to the recent widespread use of the Internet, distribution of music with so-called EC (Electronic Commerce) has been developed, in which desired music data is downloaded from a homepage using a PC (Personal Computer) and the bill is charged to a credit card, for instance. The widespread of the music distribution through the Internet using the EC (referred to xe2x80x9celectronic music distributionxe2x80x9d in this specification) would reduce the necessity for consumers to go to record shops and might drastically change the distribution of music, which has been mainly distributed by CDs (Compact Discs).
Meanwhile, many people listen to music not only at home but also on their way to office, school, home, and in a car using a portable playback apparatus and the like. In these cases, music data must be recorded on a portable medium such as an MD (Mini Disc).
Regarding electronic music distribution, delivery companies adopt a variety of encryption systems to protect copyrights. More specifically, a different optimum encryption system is adopted according to the manufacturing company, the distribution route, the usage pattern, and the like. Under the circumstances, when music data that has been distributed through an electronic music distribution system is recorded on an MD, the playback apparatus is required to decode the music data on the MD according to the adopted encryption method. As a result, the playback apparatus is bulky, expensive, and not useful for users.
It is useful for users when music data that has been distributed through an electronic music distribution system is decoded at the time of recording on an MD since playback apparatuses can be inexpensive.
In this case, however, unauthorized duplication of music data is encouraged, so that the copyright of music data cannot be fully protected.
It is accordingly an object of the present invention to provide a digital data recording apparatus, a digital data recording method, and a computer-readable recording medium for protecting copyrights and reproducing music data recorded on a recording medium with an inexpensive digital data playback apparatus.
The above-mentioned object may be achieved by a digital data recording apparatus for recording digital data on a recording medium that may include: a communication unit for receiving encrypted digital data via a digital network; a decryption unit for decrypting the encrypted digital data that has been received by the communication unit; an encryption unit including a plurality of encryption sub-units that re-encrypt decrypted digital data in encryption systems having different security levels; a recording unit for recording digital data that has been re-encrypted by the encryption unit on the recording medium; and a controller for controlling the decryption unit and the encryption unit, wherein the controller has one of the plurality of encryption sub-units re-encrypt the digital data that has been decrypted by the decryption unit.
As a result, it is possible to record digital data that has been re-encrypted by the encryption unit and can be easily reproduced by the playback apparatus. It is also possible to protect the copyright since the digital data has been re-encrypted.
The above-mentioned object may be also achieved by the digital data recording apparatus, wherein the digital data that has been recorded on the recording medium is reproduced by a playback apparatus, the encryption unit includes: a first encryption sub-unit for re-encrypting digital data using an encryption key that has been created according to identification information of the recording medium; and a second encryption sub-unit for re-encrypting digital data using an encryption key that has been created according to identification information of the playback apparatus; and the controller judges whether the recording medium is removable from the playback apparatus, has the first encryption sub-unit re-encrypt the decrypted digital data when the recording medium is removable from the playback apparatus, and has the second encryption sub-unit re-encrypt the decrypted digital data when the recording medium is not removable from the playback apparatus.
As a result, when digital data on a recording medium is reproduced by a playback apparatus, the digital data may be reproduced by re-encrypting the digital data using an encryption key that has been created according to the identification information of the recording medium. On the other hand, when digital data on a recording medium is reproduced by a specific playback apparatus, the digital data may be reproduced by the specific playback apparatus by re-encrypting the digital data using an encryption key that has been created according to the identification information of the specific playback apparatus.
The above-mentioned object may be also achieved by the digital data recording apparatus that may include an accounting unit for conducting an accounting process via the digital network, wherein the controller determines an accounting value according to an encryption sub-unit that has re-encrypted the decrypted digital data, and controls the accounting unit so that the controller conducts the accounting process according to the determined accounting value.
As a result, it is possible to select one of the plurality of encryption sub-units that re-encrypt digital data in encryption systems having different security levels and to pay a charge according to the selected encryption sub-unit.
The above-mentioned object may be also achieved by the digital data recording apparatus, wherein the controller prohibits the decryption unit from decrypting the encrypted digital data when the encryption unit fails to create any encryption key.
As a result, unnecessary decryption of digital data may be prevented when the encryption unit fails to create any encryption key.
The above-mentioned object may be also achieved by the digital data recording apparatus, wherein the security levels of the encryption systems in which the plurality of encryption sub-units re-encrypt decrypted digital data are lower than security levels of encryption systems in which encrypted digital data that are to be received by the communication unit have been encrypted.
As a result, a playback apparatus may easily reproduce digital data, leading to a less expensive playback apparatus.
The above-mentioned object may be also achieved by the digital data recording apparatus, wherein the encrypted digital data that is received by the communication unit has been encrypted in one of encryption systems having different security levels and includes attribute information that indicates the encryption system, the decryption unit includes a plurality of decryption sub-units that decrypt encrypted digital data that have been encrypted in the encryption systems, and the controller judges the encryption system in which the encrypted digital data has been encrypted according to the attribute information, and controls the decryption unit so that one of the plurality of decryption sub-units corresponding to the judged encryption system decrypts the encrypted digital data.
As a result, even when received digital data have been encrypted in encryption systems having different security levels, it is possible to decrypt digital data by selecting a decryption sub-unit according to the encryption system in which the digital data has been encrypted.
The above-mentioned object may be also achieved by the digital data recording apparatus that may further include an accounting unit for conducting an accounting process via the digital network, wherein the controller determines an accounting value according to a decryption sub-unit that has decrypted the encrypted digital data and an encryption sub-unit that has re-encrypted the decrypted digital data, and controls the accounting unit so that the controller conducts the accounting process according to the determined accounting value.
As a result, it is possible to pay a charge according to the decryption and re-encryption of digital data and to protect the copyright.
The above-mentioned object may be also achieved by a digital data recording method of recording digital data on a recording medium, the digital data recording method may include: a communication step for receiving encrypted digital data via a digital network; a decryption step for decrypting the encrypted digital data that has been received at the communication step; an encryption step for re-encrypting decrypted digital data in one of a plurality of encryption systems having different security levels; and a recording step for recording digital data that has been re-encrypted at the encryption step on the recording medium.
As a result, it is possible to record digital data on a recording medium that has been re-encrypted in an encryption system so that the digital data is easily reproduced by a playback apparatus. In addition, since the digital data is re-encrypted, the copyright may be protected.
The above-mentioned object may be also achieved by the digital data recording method, wherein the encrypted digital data that is received at the communication step has been encrypted in one of encryption systems having different security levels and includes attribute information that indicates the encryption system, the digital data recording method, further comprising a judging step for judging one of the plurality of encryption systems according to the attribute information, wherein the decryption step decrypts the encrypted digital data according to the judgement at the judging step.
As a result, digital data that has been recorded on a recording medium may be reproduced by any playback apparatus or only by a specific playback apparatus.
The above-mentioned object may be also achieved by a computer-readable recording medium that is applied to a digital data recording apparatus for recording digital data on a first recording medium, the computer-readable recording medium storing a program that has a computer execute steps: a communication step for receiving encrypted digital data via a digital network; a decryption step for decrypting the encrypted digital data that has been received at the communication step; an encryption step for re-encrypting decrypted digital data in one of a plurality of encryption systems having different security levels; and a recording step for recording digital data that has been re-encrypted at the encryption step on the recording medium.
As a result, it is possible to record digital data on a recording medium that has been re-encrypted in an encryption system so that the digital data is easily reproduced by a playback apparatus. In addition, it is possible to protect copyrights by using the recording medium in a digital data recording apparatus that has no function to protect copyrights.
The above-mentioned object may be also achieved by the computer-readable recording medium, wherein the encrypted digital data that is received at the communication step has been encrypted in one of encryption systems having different security levels and includes attribute information that indicates the encryption system, the digital data recording method may further include a judging step for judging one of the plurality of encryption systems according to the attribute information, wherein the decryption step decrypts the encrypted digital data according to the judgement at the judging step.
As a result, it is possible to reproduce digital data that has been recorded on the first recording medium by any playback apparatus or by a specific apparatus.